Fabrication, Calibration and Testing of a Transient Hot-Wire Thermal Conductivity Apparatus for Nanosilica-in-Fluid Dispersion (Nanofluids)

Philippine Journal of Agricultural and Biosystems Engineering; Sheryl Lynn Flores; Adrian Augusto Sumalde; Ma. Cristine Concepcion Ignacio; John Paolo Ramoso; Aryan Paula Manalo

doi:10.48196/013.01.2017.04

Philippine Journal of Agricultural and Biosystems Engineering
Sheryl Lynn Flores University of the Philippines Los Banos
Adrian Augusto Sumalde University of the Philippines Los Banos
Ma. Cristine Concepcion Ignacio University of the Philippines Los Banos
John Paolo Ramoso University of the Philippines Los Banos
Aryan Paula Manalo University of the Philippines Los Banos

DOI: https://doi.org/10.48196/013.01.2017.04

Keywords: nanofluids, transient hot-wire, thermal conductivity, Wheatstone bridge

Abstract

The field of nanotechnology is developing at an increasing rate, and studies have been focused in characterizing the properties of nanomaterials in order to further their applications. In this study, a Wheatstone bridge network was incorporated along with a thermal conductivity cell setup in order to determine the thermal conductivity of nanofluids with a certain degree of accuracy and precision. The Wheatstone bridge is balanced using a DC electronic load, and with the measured voltage output and resistance values, the temperature change of a platinum hot-wire is calculated using voltage divider rule. The slope of the temperature change with respect to time in the logarithmic scale is used to compute the thermal conductivity of the fluid. The fabricated apparatus is calibrated using distilled water, with the obtained percent error between measured and standard values ranging from 0.0019% to 1.015%. Further validation of the apparatus was done statistically, with the results supporting the accuracy of the fabricated apparatus. Finally, the apparatus was tested to determine the conductivity of several test fluids composed of ethylene glycol (EG), water and nanosilica (NS), and its precision was validated with repeated measurements on a specific nanofluid 25 EG, 75 H2O 0.25% NS.